In the manufacture of components which are to be used in a product, such as an automobile, it is a common practice to subject selected components to test procedures for purposes of quality assurance. Such test procedures may include testing in which the component is subjected to motions and forces which simulate the actual use for which it is designed or other motions and forces selected according to other criteria. Also, testing of components by subjecting them to programmed motions and forces is useful in the development and design of such components and parts.
The need for such testing is commonplace in the automotive industry. A particular example is an automotive power steering unit of the rack and pinion type with hydraulic assist. This vehicle component comprises a body for mounting of the vehicle chassis and containing the rack and pinion and hydraulic actuator and having a steering column input shaft to the pinion. Each end of the rack is coupled through a pivotable tie rod with the steering arm of one of the front vehicle wheels. Testing apparatus for such a mechanism heretofore known leaves much to be desired especially in respect to simulating the motions and forces to which the mechanism is subjected during actual use.
Testing apparatus is known for vehicle steering mechanisms wherein the tie rods are subjected to programmed motions and forces during programmed actuation of the steering column input to the mechanism. In the known testing apparatus, servo systems are used for sequentially pivoting the tie rods to predetermined angles and, while the angular positions are maintained, the tie rods are subjected to programmed forces. Such a testing procedure is very time consuming. Furthermore, since the tie rods are subjected to test forces only at discrete angular positions, it does not simulate actual operating conditions.
A general object of this invention is to provide an improved test apparatus which overcomes certain disadvantages of the prior art.